Thiopurine-treated Patients Research Articles

Cumulative thiopurine dosing and keratinocyte skin cancer in inflammatory bowel disease: a case-control study.

Patients with inflammatory bowel disease (IBD) treated with thiopurines are at increased risk of keratinocyte skin cancer (KSC). Most international guidelines recommend yearly dermatological screening of thiopurine-treated patients. Whether the association between the development of KSC and the use of thiopurines is dose-dependent remains unclear. The aim of this study was to investigate the association between the cumulative thiopurine dose and KSC development in patients with IBD which can be helpful to assist in further skin cancer risk stratification and personalization of screening recommendations in patients with IBD. We performed a single-center case-control study, including patients with IBD with and without a history of KSC (cases and controls, respectively). The primary outcome was the association of cumulative azathioprine, mercaptopurine and thioguanine dose with KSC development. Univariable and multivariable logistic regression analyses were performed, the latter corrected for age and smoking, known risk factors of KSC. We included 50 cases and 150 controls, predominantly white population. Age and current azathioprine use were univariably significantly associated with KSC development. In multivariable logistic regression analyses, age at inclusion remained significantly associated. Cumulative doses of thiopurines (separate or combined) or duration of thiopurine use did not impact KSC risk, also after correcting for age and smoking. Cumulative thiopurine dose and duration did not show an association with KSC development. Future KSC risk stratification, based on all available KSC risk factors, may aid in selecting individuals who can benefit most from dermatologic screening programs.

Feasibility of Reduced Clinical Monitoring in Patients with Inflammatory Bowel Disease Treated with Thiopurine Therapy

BackgroundOutpatient visits and laboratory assessments are routinely scheduled every 3 to 4 months in thiopurine-treated patients with inflammatory bowel disease (IBD) to timely detect thiopurine-related adverse events (AEs). AEs that require therapy adjustment beyond 12 months of treatment are rare.Aim and MethodsThis single-center prospective cohort study evaluated the safety of a reduced 6-monthly monitoring strategy in steroid-free patients with quiescent IBD on stable dose of azathioprine, mercaptopurine, or thioguanine monotherapy. The primary outcome was thiopurine-related AEs requiring therapy adjustments during a follow-up period of 24 months. Secondary outcomes included all AEs including laboratory toxicity, disease flares until 12 months, and the net monetary benefit from this strategy concerning IBD-related health care use.ResultsWe enrolled 85 patients with IBD (median age 42 years, 61% Crohn’s disease, 62% female), with a median disease duration of 12.5 years and median thiopurine treatment duration of 6.7 years. During follow-up, 3 patients (4%) ceased thiopurines due to AEs: recurrent infections, non-melanoma skin cancer, and gastrointestinal complaints (nausea, vomiting). At 12 months, 25 laboratory toxicities were observed (including 13% myelotoxicity, 17% hepatotoxicity); none required therapy adjustments and all were transient. A reduced monitoring strategy had a net benefit of €136 per patient.ConclusionThree patients (4%) ceased thiopurine therapy due to thiopurine-related AEs, while no laboratory toxicity required therapy adjustments. Monitoring frequency of every 6 months seems feasible in patients with stable IBD on long-term (median duration > 6 years) maintenance thiopurine therapy and may contribute to reduced patient-burden and health care costs.

P905 Predictive pharmacogenetic risk of pancreatitis in Inflammatory Bowel Disease patients treated with thiopurines: a case-control study from the ENEIDA registry

Abstract Background Treatment with thiopurines may be associated with different adverse effects, including acute pancreatitis. Risk factors for developing pancreatitis due to thiopurines in patients with Inflammatory Bowel Disease (IBD) are not clearly identified, with underlying genetic predisposition being a possible cause. Our aim was to evaluate predictive pharmacogenetic risk of pancreatitis in IBD patients treated with thiopurines. Methods IBD patients treated with thiopurines were identified from the prospectively maintained ENEIDA registry of the Spanish Working Group on Crohn’s Disease and Ulcerative Colitis (GETECCU). We included as cases those patients who met the Atlanta diagnostic criteria for pancreatitis and had an imaging test that ruled out biliary origin. We included as controls those patients without pancreatitis after at least two years of treatment with thiopurines. Blood samples were collected, and DNA was extracted from leukocytes for all participants and, subsequently, pooled samples were sequenced. Sequencing of a panel of genes (CASR, CEL, CDLN2, CFTR, CPA1, CTRC, PRSS1, and SPINK1) was carried out in the NextSeq500 platform. Variants detected were classified as pathogenic, variants of unknown significance, and benign according to the American College of Medical Genetics and Genomics (ACMGG) guidelines. Results Ninety-five cases and 105 controls were enrolled, 57% were women. Pancreatitis was diagnosed at a median age of 39±13 years old. No patient had previous history of chronic or acute pancreatitis. There were no differences between thiopurine-treated patients with and without pancreatitis in age, sex, and age at IBD onset. We identified 81 benign variants (50 in cases and 67 in controls) and a total of 35 distinct rare pathogenic and unknown significance variants (10 in CEL, 21 in CFTR, 1 in CDLN2, and 3 in CPA1). Of these 35 variants (12 in cases and 18 in controls), 6 were classified as pathogenic (1 in cases and 5 in controls), belonging to the CEL and CFTR genes, and 30 as variants of uncertain significance (21 in cases and 22 in controls). There were no significant differences between the groups of cases and controls, both in totals and by genes. None of the cases or controls carried pancreatitis-predisposing variants within the CASR, CPA1, PRSS1, and SPINK1 genes. None of the analysed samples with pancreatitis carried a pathogenic CFTR mutation. Four different variants of unknown significance were detected in the CDLN and CPA1 genes. One of them was in the CDLN gene in a single patient with pancreatitis, and 3 variants in the CPA1 gene in 5 control individuals. Conclusion In patients with IBD, there is no predisposition to thiopurine-induced pancreatitis associated with genes known to cause pancreatitis.

P460 A Real-World Picture of Adverse Drug Reactions in Inflammatory Bowel Disease

Abstract Background Patients with Inflammatory Bowel Disease (IBD) face complications of medical treatment that may compromise their health and the drugs’ therapeutic success. Real world data regarding adverse drug reactions (ADR) is crucial. Methods Unicentric retrospective study. All patients followed for IBD in a tertiary Portuguese hospital between 2015–2021 were included. Results 328 patients included-55.8% women; age at last follow-up 53.4±16.7 years old; Crohn’s Disease (CD) in 53.0%; follow-up of 15.8±10.8years. Extraintestinal manifestations(EIM) occurred in 13.1%(n=43) patients, mostly arthropathy/arthritis(n=33). Current or previous treatment included salicylates in 69.5%, thiopurines 63.1%, corticosteroids 54.3%, methotrexate 5.5%, infliximab 38.4%, adalimumab 11.6%, ustekinumab 4.9% and vedolizumab 4.6%. In total, 124 ADR occurred in 97 patients(28.7%). ADR occurred with salicylates in 20/228 patients(8.8%), corresponding to 9/215 of mesalazine and 10/26 of salazopyrin treated patients, mostly gastrointestinal(GI) intolerance(n=8). ADR occurred in 78/207(37.7%) of thiopurine-treated patients; 5 had more than one ADR to thiopurines and 10 developed ADR despite change from azathioprine to 6-mercaptopurine. Reactions included myelosuppression(n=21), GI symptoms(n=20), pancreatitis(n=8). One case of corticosteroid ADR was reported (psychosis). 4/18(22,2%) methotrexate-treated patients experienced ADR, all liver toxicity. Infliximab-associated ADR occurred in 20/126 patients(6.1%), namely infusion reactions(n=7) or lupus-like syndrome(LLS) (n=6). 9/39 adalimumab-treated patients experienced ADR, such as skin rash(n=3). No reported ADR with ustekinumab or vedolizumab. Overall, ADR led to dose adjustments in 100/120 cases and to drug suspension in 22. Nine patients needed hospital admission and one died with squamous cell carcinoma in fistula tracts. 94.9% of these ADR remitted. In the univariate analysis, ADR were associated with IBD type(p=0.040), EIM(p=0.001), UC extent(p=0.016), thiopurine(p<0.001), infliximab(p<0.001) and adalimumab (p=0.005) exposure. In multivariate analysis, significance was kept with EIM(p=0.003), thioupurine(p=0.006) and infliximab(p=0.003) exposure. Patients who had one ADR, were not more likely to have ADR with other drugs. Conclusion ADR occurred in 28.7% of IBD patients and the most commonly implicated drugs were salazopyrin (10/26, 38.5% of patients) and thiopurines (75/207, 36.2%), rates much higher than those found with mesalazine and biologics. Nevertheless, most of these reactions resolved with dose adjustments or drug suspension, without hospital admission. This indicates that drugs available for IBD treatment remain safe, but their use must be cautious and toxicities should be monitored.

Diagnostic accuracy of NUDT15 gene variants for thiopurine-induced leukopenia: a systematic review and meta-analysis

We herein conducted a systematic review and meta-analysis of published studies to estimate diagnostic accuracy of NUDT15 gene polymorphisms for detection of thiopurine-induced leukopenia. Eligible studies were identified through a comprehensive search on PubMed, Web of Knowledge, Cochrane and OpenGrey datasets up to April 2018. The methodological quality of eligible studies was assessed using the QUADAS-2 criteria. The diagnostic odds ratio (DOR) was used as a single measure of diagnostic performance. Sixteen studies including a total of 3538 thiopurine-treated patients fulfilled inclusion criteria for the systematic review. Among these, 16 studies were available for the meta-analysis of rs116855232, 6 studies for rs186364861 and 5 studies for rs554405994 of NUDT15. A higher DOR was found for rs116855232 (8.44, 95% CI: 5.46-13.03), as compared to rs554405994 (4.336, 95% CI 2.924-6.429) or rs186364861 (2.742, 95% CI 1.453-5.175). Results of meta-regression analysis showed that incidence of leukopenia (relative DOR: 0.96; 95%CI: 0.93-1.00, p = 0.037) and leukopenia onset (late vs early leukopenia, relative DOR: 0.41, 95% CI 0.20-0.85, p = 0.0189) significantly influenced diagnostic accuracy of rs116855232. Subgroup analysis for rs186364861 and rs554405994 revealed a significant DOR for early-onset leukopenia (rs186364861: 4.04, 95% CI 1.78-9.20; rs554405994: 2.94, 95% CI 1.74-4.95), but not for late-onset leukopenia (rs186364861: 1.52, 95% CI 0.52-4.43; rs554405994: 2.02, 95% CI 0.93-4.40). The present meta-analysis points to rs116855232, rs554405994 and rs186364861 of NUDT15 as clinically relevant predictors of thiopurine-induced leukopenia. Nevertheless, prospective studies of genotype-guided dosing of thiopurines are warranted to prove clinical benefit and cost-effectiveness of pretreatment NUDT15 gene testing across different populations.

Clinical Course of Nodular Regenerative Hyperplasia in Thiopurine Treated Inflammatory Bowel Disease Patients

Nodular regenerative hyperplasia (NRH) is a poorly understood liver condition, which is increasingly recognized in thiopurine-treated patients with inflammatory bowel disease (IBD).1 It is difficult to establish an optimal approach to NRH patients, because its manifestations are highly variable (from asymptomatic to symptoms of noncirrhotic portal hypertension [NCPH]) and the prognosis is unknown.2 The aim of this study was to identify NRH cases in IBD patients treated with azathioprine, mercaptopurine, and/or thioguanine, and to describe its clinical course.

Thiopurine Treatment in Ulcerative Colitis: A Critical Review of the Evidence for Current Clinical Practice.

Due to toxicity problems and controversial evidence, thiopurine use in ulcerative colitis (UC) has faced a lot of criticism. We present a critical review of the literature on efficacy of thiopurines in UC. Studies evaluating therapeutic efficacy of thiopurine remission induction and/or maintenance treatment in UC were identified using the Cochrane Library, MEDLINE, and EMBASE. Out of 5 randomized trials on thiopurine induction treatment, 3 demonstrated a significant effect of thiopurine treatment vs mesalamine or placebo in steroid-dependent UC patients: (1) lower endoscopic activity scores, (2) higher clinical remission rates, and (3) more patients who discontinued steroids. Two found no significant difference in clinical and endoscopic remission of azathioprine compared with sulfasalazine or placebo in patients with active UC. Out of 7 randomized trials on thiopurine maintenance treatment, 4 demonstrated significant higher clinical and endoscopic remission rates in thiopurine-treated patients compared with placebo or mesalamine. Three found no significant difference in clinical and endoscopic remission of thiopurine maintenance treatment compared with sulfasalazine or placebo. All studies that investigated thiopurine treatment in UC had shortcomings, such as lack of sufficient power, no use of blinding, allowed concomitant treatment with steroids, and no endoscopy to confirm active disease at study entry or to evaluate therapeutic efficacy. Hence, current clinical practice of thiopurine treatment in UC is based on minimal and controversial evidence. This underscores the need for clinical studies with sufficient power and objective end points in order to determine efficacy of thiopurines in UC.

Determination of inosine 5'-monophosphate dehydrogenase activity in red blood cells of thiopurine-treated patients using HPLC.

Thiopurine drugs are commonly used in immune diseases and to a lesser extent, in transplant rejection prophylaxis: however interindividual variability in drug response and in the occurrence of adverse events is observed. Genetic variation in thiopurine S-methyltransferase (TPMT) doesn't completely explain the occurrence of all adverse events and drug response variability. The potential implication of other enzymes involved in thiopurine metabolism, such as ITPA, has been investigated over the last decade but little data is available on inosine 5'-monophosphate dehydrogenase (IMPDH) in patients treated with thiopurine drugs. The authors reported a HPLC method to determine IMPDH activity in the red blood cells (RBCs) of thiopurine-treated patients. IMPDH activity was evaluated by enzymatic conversion of inosine 5'-monophosphate (IMP) to xanthosine 5'-monophosphate (XMP). The XMP formed was analyzed on a Luna® NH2 stationary phase, a weak anion exchange phase that exhibits both ionic and hydrophobic properties. XMP was eluted below 15min. Intra-assay and inter-assay precisions were below 9% for RBCs supplemented with 2, 40 and 80μmol/L of XMP. IMPDH activity was measured in adults without thiopurine treatment as well as in adult and paediatric patients treated with thiopurines. A wide interindividual variability in IMPDH activity in RBCs was observed. No difference in IMPDH activity was found between untreated subjects and adult and paediatric patients on thiopurine therapy (median value 11.8, 7.9 and 7.7nmol XPM/g Hb/h respectively). The method described is useful in the determination of IMPDH phenotype from patients on thiopurine therapy and in the investigation of the potential relationship between IMPDH activity in RBCs and the occurrence of adverse events and drug response variability.

NUDT15, FTO, and RUNX1 genetic variants and thiopurine intolerance among Japanese patients with inflammatory bowel diseases.

Background/AimsRecent genome-wide analyses have provided strong evidence concerning adverse events caused by thiopurine drugs such as azathioprine (AZA) and 6-mercaptopurine. The strong associations identified between NUDT15 p.Arg139Cys and thiopurine-induced leukopenia and severe hair loss have been studied and confirmed over the last 2 years. However, other coding variants, including NUDT15 p.Val18_Val19insGlyVal, NUDT15 p.Val18Ile, and FTO p.Ala134Thr, and a noncoding variation in RUNX1 (rs2834826) remain to be examined in detail in this respect. Therefore, we investigated the correlation between these adverse events and the 5 recently identified variants mentioned above among Japanese patients with inflammatory bowel diseases (IBD).MethodsOne hundred sixty thiopurine-treated patients with IBD were enrolled. Genotyping was performed using TaqMan SNP Genotyping Assays or Sanger sequencing.ResultsNone of the 5 variants were associated with gastrointestinal intolerance to AZA. However, NUDT15 p.Arg139Cys was significantly associated with the interval between initiation and discontinuation of AZA among patients with gastrointestinal intolerance. This variant was strongly associated with early (<8 weeks) and late (≥8 weeks) leukopenia and severe hair loss. Moreover, it correlated with the interval between initiation of thiopurine therapy and leukopenia occurrence, and average thiopurine dose. NUDT15 p.Val18_Val19insGlyVal, NUDT15 p.Val18Ile, FTO p.Ala134Thr, and RUNX1 rs2834826 exhibited no significant relationship with the adverse events examined.ConclusionsOf the 5 variants investigated, NUDT15 p.Arg139Cys had the strongest impact on thiopurine-induced leukopenia and severe hair loss; therefore, its genotyping should be prioritized over that of other variants in efforts to predict these adverse events in Japanese patients with IBD.

A coding variant in FTO confers susceptibility to thiopurine-induced leukopenia in East Asian patients with IBD

ObjectiveMyelosuppression is a life-threatening complication of thiopurine therapy, and the incidence of thiopurine-induced myelosuppression is higher in East Asians than in Europeans. We investigated genetic factors associated with thiopurine-induced leukopenia...

Liquid chromatography-mass spectrometry for measuring deoxythioguanosine in DNA from thiopurine-treated patients.

Adverse reactions and non-response are common in patients treated with thiopurine drugs. Current monitoring of drug metabolite levels for guiding treatment are limited to analysis of thioguanine nucleotides (TGNs) in erythrocytes after chemical derivatisation. Erythrocytes are not the target tissue and TGN levels show poor correlations with clinical response. We have developed a sensitive assay to quantify deoxythioguanosine (dTG) without derivatisation in the DNA of nucleated blood cells. Using liquid chromatography and detection by tandem mass spectrometry, an intra- and inter-assay variability below 7.8% and 17.0% respectively were achieved. The assay had a detection limit of 0.0003125ng (1.1 femtomoles) dTG and was quantified in DNA samples relative to endogenous deoxyadenosine (dA) in a small group of 20 patients with inflammatory bowel disease, all of whom had been established on azathioprine (AZA) therapy for more than 25 weeks. These patients had dTG levels of 20-1360mol dTG/10(6)mol dA; three patients who had not started therapy had no detectable dTG. This method, comparable to previous methods in sensitivity, enables the direct detection of a cytotoxic thiopurine metabolite without derivatisation in an easily obtainable, stable sample and will facilitate a better understanding of the mechanisms of action of these inexpensive yet effective drugs.

EBV Status and Thiopurine Use in Pediatric IBD.

Epstein Barr virus (EBV) is a human herpes virus that infects 90% of the world's population and has been linked to the development of lymphoproliferative disorders (LPDs) and immunosuppression. Primary EBV infection in patients with IBD on thiopurines is a risk factor for LPD, including lymphoma. We aimed to describe EBV status in a pediatric population with IBD with an emphasis on those initiating thiopurines. Electronic medical records and EBV serologies were reviewed and categorized into asymptomatic screening versus suspicion for acute infection. EBV status before therapy was described by sex, age, and therapeutic regimen. Descriptive statistics and univariate analysis were employed. Only 150 (22%) of our 688 pediatric patients with IBD had documented EBV status regardless of age or treatment regimen. Only 17% were assessed for suspicion of acute infection and 83% for screening. Sixty-four (52%) screened patients were checked before starting any treatment and only 40% were immunoglobulin (Ig)G positive. There was no difference in mean age between the seronegative and seropositive group. The majority (63%) of thiopurine-treated patients were IgG negative before starting therapy. Eighty percent of primary EBV infections occurred on thiopurines at a mean (SD) of 2 ± 1.5 years after initiating therapy. The majority of our pediatric patients with IBD with documented EBV status were IgG negative at thiopurine initiation. Thiopurines were also associated with primary EBV infection. EBV status may be an important determinate of whether physicians prescribe thiopurines given the risk of primary EBV infections and lymphoproliferative diseases.

Does lymphopenia or macrocytosis reflect 6‐thioguanine levels in patients with inflammatory bowel disease treated with azathioprine or 6‐mercaptopurine?

The thiopurine drugs, 6-mercaptopurine and azathioprine, remain the mainstay of immunomodulator therapy for inflammatory bowel disease (IBD). Optimal management depends on achieving therapeutic levels of 6-thioguanine (6-TGN), but measuring thiopurine metabolites is associated with significant cost. Thiopurines cause lymphopenia and an increase in mean corpuscular volume (MCV). It is unclear whether any clinically useful correlation exists between 6-TGN levels and lymphocyte count or MCV. The aim of this study is to investigate the correlation between 6-TGN levels and lymphocyte count and MCV in thiopurine-treated patients with IBD. We analysed a prospectively acquired database of 67 patients with IBD treated with thiopurine therapy. The data were analysed looking at the relationship between 6-TGN levels and both lymphocyte count and MCV by using the Spearman's rank correlation coefficient. Twenty-seven (40%) patients had therapeutic 6-TGN levels. Thirty-three (49%) patients had sub-therapeutic 6-TGN levels. A weak positive correlation between 6-TGN levels and lymphocyte count was demonstrated, but this was not statistically significant (Spearman's R = 0.14, P = 0.23). Spearman's rank correlation coefficient between 6-TGN levels and MCV was statistically significant (R = 0.42, P = 0.0005). MCV >101 fL excluded a subtherapeutic 6-TGN level with positive predictive value of 92%. There is no specific lymphopenia that can be assumed to indicate a therapeutic 6-TGN level. The relationship between 6-TGN levels and MCV is likely to be clinically relevant. If MCV is elevated, 6-TGN is unlikely to be sub-therapeutic. MCV is a potential surrogate marker which can rule out sub-therapeutic thiopurine metabolites in patients with IBD treated with azathioprine or 6-mercaptopurine.

Risk of melanoma and non-melanoma skin cancer in ulcerative colitis patients treated with thiopurines: a nationwide retrospective cohort.

There are limited data on the risk of non-melanoma skin cancer (NMSC) and melanoma skin cancer (MSC) among thiopurine-treated patients with ulcerative colitis (UC). Our aim was to investigate the risk while on, by cumulative years, and after stopping thiopurine therapy. Nationwide data were obtained from the Veterans Affairs (VA) health-care system during 2001-2011. We performed a retrospective cohort study evaluating patients with UC. Cox regression was used to investigate the association between thiopurines use and time to NMSC while adjusting for demographics, ultraviolet radiation exposure, and VA visiting frequency. A matched nested case-control study was conducted to investigate the association between thiopurine use and MSC. We included 14,527 patients with UC in the analysis, with a median follow-up of 8.1 years. A total of 3,346 (23%) patients used thiopurines for a median duration of 1.6 years. We identified 421 NMSC and 45 MSC cases. The adjusted hazard ratios of developing NMSC while on and after stopping thiopurines were 2.1 (P<0.0001) and 0.7 (P=0.07), respectively, as compared with unexposed patients. The incidence rate of NMSC among those who never used thiopurines was 3.7 compared with 5.8, 7.9, 8.3, 7.8, and 13.6 per 1,000 person-years for the 1st, 2nd, 3th, 4th, and 5th year of thiopurine use, respectively. No statistically significant association was observed between thiopurine use and MSC, odds ratio 0.8 (P=0.6). In this predominantly white male nationwide cohort, there was a twofold increase in the risk of NMSC while on thiopurines. The incidence rate of NMSC significantly increased with subsequent years of cumulative exposure to thiopurines. Stopping thiopurines reduced the risk of NMSC to pre-exposure levels irrespective of the prior exposure duration.

Use of thiopurines and risk of colorectal neoplasia in patients with inflammatory bowel diseases: a meta-analysis.

ObjectiveInflammatory bowel disease (IBD) is commonly treated with thiopurines such as azathioprine and mercaptopurine for the maintenance of remission. Studies examining chemopreventive of these medications on colorectal neoplasm in IBD patients have yielded conflicting results. We performed a meta-analysis to assess the role of thiopurines for this indication.MethodsWe performed a systematic search of PubMed, Web of Science, EMBASE and Cochrane to identify studies reporting colorectal neoplasm from IBD patients treated with thiopurines and conducted a meta-analysis of pooled relative risk (RR) using the random effects model.ResultsNine case-control and ten cohort studies fulfilled the inclusion criteria. The use of thiopurines was associated with a statistically significant decreased incidence of colorectal neoplasm (summary RR=0.71, 95% CI=0.54–0.94, p=0.017), even after adjustment for duration and extent of the disease, but there was high heterogeneity among studies (I 2=68.0%, p<0.001). The RR of advanced neoplasm (high-grade dysplasia and cancer) was 0.72 (95%CI=0.50–1.03, p=0.070) and that of cancer was 0.70 (95% CI=0.46–1.09, p=0.111) for thiopurine-treated patients. Heterogeneity of the studies was affected by the sample size (</≥100 cases) and whether the patients had longstanding colitis (≥7 years).ConclusionThe current meta-analysis revealed that thiopurines had a chemopreventive effect of colorectal neoplasms and a tendency of reducing advanced colorectal neoplasms in IBD. Due to the heterogeneity of included studies, these results should be interpreted with caution.

Risk of Lymphoma in Patients With Ulcerative Colitis Treated With Thiopurines: A Nationwide Retrospective Cohort Study

There is controversy over whether the treatment of patients with ulcerative colitis (UC) with thiopurines increases their risk of lymphoma. We evaluated the risk of lymphoma (ongoing, residual, and per year of therapy) among thiopurine-treated patients with UC. We obtained nationwide data from the Veterans Affairs (VA) health care system from 2001 to 2011. We performed a retrospective cohort study, analyzing data on 36,891 patients from their date of diagnosis of UC in the VA health care system to a diagnosis of lymphoma or October 1, 2011 (subjects followed up for a median of 6.7 years). Thiopurine exposure wasassessed using the VA pharmacy database. Patients who developed lymphoma were identified based on ICD-9 codes and confirmed by manual chart review. In total, 4734 patients with UC (13%) were treated with thiopurines for a median of 1 year. Lymphoma developed in 119 patients who had not been treated with thiopurines, 18 who were treated with thiopurines, and 5 whohad discontinued treatment with thiopurines. The incidence rates of lymphoma were 0.60 per 1000 person-years among patients who had not been treated with thiopurines, 2.31 among patients who were treated with thiopurines, and 0.28 among patients who had discontinued treatment with thiopurines. The incidence rates of lymphoma during the first year, second year, third year, fourth year, and >4 years of thiopurine therapy were 0.9, 1.6, 1.6, 5, and 8.9 per 1000 person-years, respectively. The age-, sex-, and race-adjusted hazard ratios of developing lymphoma were 4.2 (95% confidence interval, 2.5-6.8; P < .0001) while being treated withthiopurines and 0.5 (95% confidence interval, 0.2-1.3; P= .17) after discontinuing treatment with thiopurines compared with patients who had not been treated with thiopurines. Based on a retrospective, nationwide cohort study, patients with UC have a 4-fold increase in risk of lymphoma while being treated with thiopurines compared with patients who have not been treated with thiopurines. The risk increases gradually for successive years of therapy. Discontinuing thiopurine therapy reduces the risk of lymphoma.

Thiopurine Effectiveness in Patients with Crohnʼs Disease

Thiopurines are efficacious in the treatment of Crohn's disease and were recently shown to induce T-cell apoptosis by modulation of Rac1 activation. To assess whether polymorphisms in Rac1 and other apoptosis-related genes, combined with clinical parameters, can predict response to thiopurines. A retrospective cohort of 156 thiopurine-treated patients with Crohn's disease was genotyped for 11 single-nucleotide polymorphisms (SNPs): 9 SNPs in Rac1, 1 SNP in the Fas ligand -843 T>C, and 1 SNP in the Caspase-9 93 C>T. Clinical data were extracted from the medical charts. Odds ratios (ORs) and 95% confidence intervals (CIs) of the association between demographic, clinical, and genetic variables and thiopurine response rates were calculated. The overall response rate to thiopurines was 74% (115/156). The Rac1 SNP rs34932801 heterozygote genotype GC was associated with a lower response rate compared with the wild-type GG genotype (46% versus 76%; OR = 0.26; 95% CI, 0.08-0.91; P = 0.036). Only wild-type homozygotes were found for 5 Rac1 SNPs. None of the other 3 Rac1 SNPs were associated with response to thiopurines. Patients with Montreal B3 behavior pattern responded worse than those with a B1 behavior pattern (59%, versus 80%; OR = 0.37; 95% CI, 0.17-0.83; P = 0.016). Sephardic Jews had a lower response rate to thiopurines compared with Jews of Ashkenazi or mixed ancestry (60% versus 82%; OR = 0.32; 95% CI, 0.15-0.69, P = 0.003). Rac1 SNP rs34932801carriage, Montreal B3 disease behavior, and a Sephardic Jewish origin were associated with unfavorable response to thiopurines. Corroboration of these associations in larger cohorts is warranted.

Multiple forms of DNA Damage Caused by UVA Photoactivation of DNA 6‐Thioguanine

Thiopurines are prescribed frequently as medication for cancer and for inflammatory disorders. One of them, azathioprine, has been the immunosuppressant of choice for organ transplant recipients for many years. Thiopurine use is associated with elevated sun sensitivity and skin cancer risk. Skin sensitization is selective for UVA. 6-TG integrates into DNA and unlike the canonical DNA bases, it is a strong UVA chromophore with an absorbance maximum at 342 nm. DNA 6-TG is a photosensitizer and a source of reactive oxygen species. Reactive oxygen that is generated from the photochemical activation of DNA 6-TG causes extensive damage to DNA and proteins. This damage is mutagenic and extremely toxic to cultured human cells. Here we describe some of the lesions that are known to be generated from UVA irradiation of DNA 6-TG. We discuss how this photochemical damage might contribute to the toxic effect of thiopurine/UVA treatment on cultured cells and to the high risk of skin cancer in thiopurine-treated patients.

Normal Response to Vaccines in Inflammatory Bowel Disease Patients Treated with Thiopurines

Thiopurines are considered immunosuppressive agents and may be associated with an increased risk for infections. However, few inflammatory bowel disease (IBD) patients are appropriately vaccinated, and data on their ability to mount an immune response are vague. We evaluated the effects of the thiopurines, azathioprine (AZA) and 6-mercaptopurine (6-MP), on cellular and humoral immune responses in IBD patients. A prospective clinical investigation was conducted on IBD patients referred for thiopurine treatment. Immune competence was evaluated by assessing lymphocyte counts and phenotype, response to mitogen and antigen stimulation, immunoglobulin levels, and response to pneumococcal and tetanus vaccines (before treatment, week 0), and to Haemophilus influenza type b vaccine (at week 24). Thirty-one Crohn's disease and 12 ulcerative colitis patients who completed at least 24 weeks of therapy were included. The posttherapy average 6-MP dose was 1.05 ± 0.30 mg/kg, and white blood cell counts had decreased significantly from baseline values (P < 0.002). The posttreatment response to mitogens and antigens and the immunoglobulin levels were unchanged. Responses to vaccines were normal both in thiopurine-naïve and thiopurine-treated patients, suggesting that these patients were immunologically intact while on thiopurine therapy and capable of generating normal immune responses in vivo. There is no evidence for any intrinsic systemic immunodeficiency in IBD patients. Thiopurines at the doses used for treating IBD showed no significant suppressive effect on the systemic cellular and humoral immune responses evaluated. Thiopurine-treated IBD patients can be safely and efficiently vaccinated.

Outcome Following Thiopurine Use in Children With Ulcerative Colitis: A Prospective Multicenter Registry Study

Despite little supporting data, thiopurine use is common in pediatric ulcerative colitis (UC). Our aim was to determine outcome following thiopurine use in a multicenter inception cohort of children diagnosed with UC. Data were obtained from a prospective observational study of newly diagnosed children <16 years of age. Data are recorded at diagnosis, 30 days, and quarterly. Patients are managed by physician dictates not protocol. Disease activity is classified by physician global assessment. The primary outcome was corticosteroid (CS)-free inactive UC at 1 year following thiopurine initiation without the need for rescue therapy (infliximab, calcineurin inhibitors, or colectomy). Of 1,490 patients in our registry, 394 have UC (mean age at diagnosis 11.3±3.7 years); 197 (50%) received thiopurine (49% ≤3 months from diagnosis). Also, 84% were receiving CSs and 60% 5-aminosalicylates at thiopurine start. Of the 197 patients, there was insufficient follow-up (41), previous or concomitant use of infliximab (16), or calcineurin inhibitor (7), leaving 133 patients evaluable at 1 year. Of these, 65 (49%) had CS-free inactive UC without rescue therapy. CS-free inactive disease at 1 year after initiating thiopurine was not affected by starting thiopurine ≤3 months vs. >3 months from diagnosis, gender, age, or concomitant treatment with 5-aminosalicylates. Kaplan-Meier analysis showed that the likelihood of remaining free of rescue therapy in the thiopurine-treated patients was 73% at 1 year. Approximately 50% of children with UC starting thiopurine without previous or concomitant biologic or calcineurin inhibitor therapy have CS-free inactive disease 1 year later without the need for rescue therapy.